| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a galvannealed steel sheet, which does not cause impairment in the appearance and a flaw originating in induction heating and electrification heating that are heating systems contributing to the improvement of the productivity, and shows a superior appearance quality, and to provide a heating facility for forming the alloy to be used in the method. SOLUTION: In a process of manufacturing the galvannealed steel sheet by annealing a steel sheet without bringing the steel sheet in contact with the atmosphere and hot-dip-galvanizing the steel sheet in a hot-dip-galvanizing facility, and heating the hot-dip-galvanized steel sheet to form an alloy therein by using either or both of an induction heating facility and an electrification heating facility, the method for obtaining the galvannealed steel sheet superior in appearance quality includes conducting the heating step for forming the alloy in an atmosphere containing 5% or less oxygen. The heating facility for forming the alloy includes a heating apparatus for forming the alloy, which is separated from the atmosphere and is provided with an atmospheric-gas-feeding facility for controlling an oxygen concentration to 5% or less. COPYRIGHT: (C)2010,JPO&INPIT
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